BEFORE YOU OPEN AN AIRCRAFT DOOR, MAKE SURE THAT THE CABIN IS NOT PRESSURIZED.TO DO THIS, MAKE SURE THAT:- THE AIR CONDITIONING GROUND-CART IS NOT CONNECTED TO THE AIRCRAFT, AND- THE FORWARD AVIONICS-COMPARTMENT ACCESS-DOOR 811 IS OPEN.IF THERE IS REMAINING PRESSURE IN THE AIRCRAFT, THE DOOR CAN OPEN WITH A SUDDENFORCE. THIS CAN CAUSE INJURY TO YOU OR KILL YOU, AND/OR CAUSE DAMAGE TO THEAIRCRAFT.